U.S. Pat. No. 2,903,767 discloses a chain tensioning and tiedown device which has come into widespread military use in fastening tiedown chains for diverse applications including securing loads such as airplanes and helicopters on the deck of an aircraft carrier. The device includes a pivotally mounted chain block defining an entrance path to receive a tensioned portion of the chain secured to the load. The block also defines an exit path from which the slack or free end of the chain emerges.
The securing device is designed to withstand heavy loading from a properly installed tensioned chain, but is less strong if the chain is inadvertently reversed during installation. That is, the structural strength of the overall tiedown system is compromised if the tensioned chain is incorrectly fed into the exit path of the chain block, and the slack free end emerges through the entrance path. Although tiedown devices of this type are placarded with a warning to avoid reverse installation of the chain, the incorrect reverse insertion can be and sometimes is made.
An important objective of this invention is to provide a novel "oriented" chain which is fully compatible with the large number of chain tiedown devices already in use, which requires no modification of the existing devices, and which prevents inadvertent reverse insertion of the chain in the device.